2 * IRC - Internet Relay Chat, ircd/engine_select.c
3 * Copyright (C) 2001 Kevin L. Mitchell <klmitch@mit.edu>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 1, or (at your option)
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 * @brief BSD sockets select() event engine.
21 * @version $Id: engine_select.c 1445 2005-07-12 03:10:59Z entrope $
25 /* On BSD, define FD_SETSIZE to what we want before including sys/types.h */
26 #if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__bsdi__)
27 # if !defined(FD_SETSIZE)
28 # define FD_SETSIZE ((MAXCONNECTIONS)+4)
32 #include "ircd_events.h"
38 /* #include <assert.h> -- Now using assert in ircd_log.h */
40 #include <string.h> /* needed for bzero() on OS X */
41 #include <sys/socket.h>
43 #include <sys/types.h>
47 #if FD_SETSIZE < (MAXCONNECTIONS + 4)
51 * All operating systems work when MAXCONNECTIONS <= 252.
52 * Most operating systems work when MAXCONNECTIONS <= 1020 and FD_SETSIZE is
53 * updated correctly in the system headers (on BSD systems sys/types.h might
54 * have abruptly redefined it so the check is still done), you might
55 * already need to recompile your kernel.
56 * For larger FD_SETSIZE your mileage may vary (kernel patches may be needed).
58 # error FD_SETSIZE is too small or MAXCONNECTIONS too large.
61 #define SELECT_ERROR_THRESHOLD 20 /**< after 20 select errors, restart */
62 #define ERROR_EXPIRE_TIME 3600 /**< expire errors after an hour */
64 /** Array of active Socket structures, indexed by file descriptor. */
65 static struct Socket* sockList[FD_SETSIZE];
66 /** Maximum file descriptor currently used. */
67 static int highest_fd;
68 /** Global read event interest bitmap. */
69 static fd_set global_read_set;
70 /** Global write event interest bitmap. */
71 static fd_set global_write_set;
73 /** Number of recent errors from select(). */
74 static int errors = 0;
75 /** Periodic timer to forget errors. */
76 static struct Timer clear_error;
78 /** Decrement the error count (once per hour).
79 * @param[in] ev Expired timer event (ignored).
82 error_clear(struct Event* ev)
84 if (!--errors) /* remove timer when error count reaches 0 */
85 timer_del(ev_timer(ev));
88 /** Initialize the select() engine.
89 * @param[in] max_sockets Maximum number of file descriptors to support.
90 * @return Non-zero on success, or zero on failure.
93 engine_init(int max_sockets)
97 if (max_sockets > FD_SETSIZE) { /* too many sockets */
98 log_write(LS_SYSTEM, L_WARNING, 0,
99 "select() engine cannot handle %d sockets (> %d)",
100 max_sockets, FD_SETSIZE);
104 FD_ZERO(&global_read_set); /* zero the global fd sets */
105 FD_ZERO(&global_write_set);
107 for (i = 0; i < FD_SETSIZE; i++) /* zero the sockList */
110 highest_fd = -1; /* No fds in set */
112 return 1; /* initialization successful */
115 /** Figure out what events go with a given state.
116 * @param[in] state %Socket state to consider.
117 * @param[in] events User-specified preferred event set.
118 * @return Actual set of preferred events.
121 state_to_events(enum SocketState state, unsigned int events)
124 case SS_CONNECTING: /* connecting socket */
125 return SOCK_EVENT_WRITABLE;
128 case SS_LISTENING: /* listening socket */
129 case SS_NOTSOCK: /* our signal socket */
130 return SOCK_EVENT_READABLE;
133 case SS_CONNECTED: case SS_DATAGRAM: case SS_CONNECTDG:
134 return events; /* ordinary socket */
142 /** Set interest events in #global_read_set and #global_write_set as appropriate.
143 * @param[in] fd File descriptor to operate on.
144 * @param[in] clear Set of interest events to clear from socket.
145 * @param[in] set Set of interest events to set on socket.
148 set_or_clear(int fd, unsigned int clear, unsigned int set)
150 if ((clear ^ set) & SOCK_EVENT_READABLE) { /* readable has changed */
151 if (set & SOCK_EVENT_READABLE) /* it's set */
152 FD_SET(fd, &global_read_set);
154 FD_CLR(fd, &global_read_set);
157 if ((clear ^ set) & SOCK_EVENT_WRITABLE) { /* writable has changed */
158 if (set & SOCK_EVENT_WRITABLE) /* it's set */
159 FD_SET(fd, &global_write_set);
161 FD_CLR(fd, &global_write_set);
165 /** Add a socket to the event engine.
166 * @param[in] sock Socket to add to engine.
167 * @return Non-zero on success, or zero on error.
170 engine_add(struct Socket* sock)
173 assert(0 == sockList[s_fd(sock)]);
175 /* bounds-check... */
176 if (s_fd(sock) >= FD_SETSIZE) {
177 log_write(LS_SYSTEM, L_ERROR, 0,
178 "Attempt to add socket %d (> %d) to event engine", s_fd(sock),
183 sockList[s_fd(sock)] = sock; /* add to list */
185 if (s_fd(sock) >= highest_fd) /* update highest_fd */
186 highest_fd = s_fd(sock);
188 Debug((DEBUG_ENGINE, "select: Adding socket %d to engine [%p], state %s",
189 s_fd(sock), sock, state_to_name(s_state(sock))));
191 /* set the fd set bits */
192 set_or_clear(s_fd(sock), 0, state_to_events(s_state(sock), s_events(sock)));
194 return 1; /* success */
197 /** Handle state transition for a socket.
198 * @param[in] sock Socket changing state.
199 * @param[in] new_state New state for socket.
202 engine_state(struct Socket* sock, enum SocketState new_state)
205 assert(sock == sockList[s_fd(sock)]);
207 Debug((DEBUG_ENGINE, "select: Changing state for socket %p to %s", sock,
208 state_to_name(new_state)));
210 /* set the correct events */
211 set_or_clear(s_fd(sock),
212 state_to_events(s_state(sock), s_events(sock)), /* old state */
213 state_to_events(new_state, s_events(sock))); /* new state */
216 /** Handle change to preferred socket events.
217 * @param[in] sock Socket getting new interest list.
218 * @param[in] new_events New set of interesting events for socket.
221 engine_events(struct Socket* sock, unsigned int new_events)
224 assert(sock == sockList[s_fd(sock)]);
226 Debug((DEBUG_ENGINE, "select: Changing event mask for socket %p to [%s]",
227 sock, sock_flags(new_events)));
229 /* set the correct events */
230 set_or_clear(s_fd(sock),
231 state_to_events(s_state(sock), s_events(sock)), /* old events */
232 state_to_events(s_state(sock), new_events)); /* new events */
235 /** Remove a socket from the event engine.
236 * @param[in] sock Socket being destroyed.
239 engine_delete(struct Socket* sock)
242 assert(sock == sockList[s_fd(sock)]);
244 Debug((DEBUG_ENGINE, "select: Deleting socket %d [%p], state %s", s_fd(sock),
245 sock, state_to_name(s_state(sock))));
247 FD_CLR(s_fd(sock), &global_read_set); /* clear event set bits */
248 FD_CLR(s_fd(sock), &global_write_set);
250 sockList[s_fd(sock)] = 0; /* zero the socket list entry */
252 while (highest_fd > -1 && sockList[highest_fd] == 0) /* update highest_fd */
256 /** Run engine event loop.
257 * @param[in] gen Lists of generators of various types.
260 engine_loop(struct Generators* gen)
272 read_set = global_read_set; /* all hail structure copy!! */
273 write_set = global_write_set;
275 /* set up the sleep time */
276 wait.tv_sec = timer_next(gen) ? (timer_next(gen) - CurrentTime) : -1;
279 Debug((DEBUG_INFO, "select: delay: %Tu (%Tu) %Tu", timer_next(gen),
280 CurrentTime, wait.tv_sec));
282 /* check for active files */
283 nfds = select(highest_fd + 1, &read_set, &write_set, 0,
284 wait.tv_sec < 0 ? 0 : &wait);
286 CurrentTime = time(0); /* set current time... */
289 if (errno != EINTR) { /* ignore select interrupts */
290 /* Log the select error */
291 log_write(LS_SOCKET, L_ERROR, 0, "select() error: %m");
293 timer_add(timer_init(&clear_error), error_clear, 0, TT_PERIODIC,
295 else if (errors > SELECT_ERROR_THRESHOLD) /* too many errors... */
296 server_restart("too many select errors");
298 /* old code did a sleep(1) here; with usage these days,
299 * that may be too expensive
304 for (i = 0; nfds && i <= highest_fd; i++) {
305 if (!(sock = sockList[i])) /* skip empty socket elements */
308 assert(s_fd(sock) == i);
310 gen_ref_inc(sock); /* can't have it going away on us */
312 Debug((DEBUG_ENGINE, "select: Checking socket %p (fd %d) state %s, "
313 "events %s", sock, i, state_to_name(s_state(sock)),
314 sock_flags(s_events(sock))));
316 if (s_state(sock) != SS_NOTSOCK) {
317 errcode = 0; /* check for errors on socket */
318 codesize = sizeof(errcode);
319 if (getsockopt(i, SOL_SOCKET, SO_ERROR, &errcode, &codesize) < 0)
320 errcode = errno; /* work around Solaris implementation */
322 if (errcode) { /* an error occurred; generate an event */
323 Debug((DEBUG_ENGINE, "select: Error %d on fd %d, socket %p", errcode,
325 event_generate(ET_ERROR, sock, errcode);
326 gen_ref_dec(sock); /* careful not to leak reference counts */
331 switch (s_state(sock)) {
333 if (FD_ISSET(i, &write_set)) { /* connection completed */
334 Debug((DEBUG_ENGINE, "select: Connection completed"));
335 event_generate(ET_CONNECT, sock, 0);
342 if (FD_ISSET(i, &read_set)) { /* connection to be accepted */
343 Debug((DEBUG_ENGINE, "select: Ready for accept"));
344 event_generate(ET_ACCEPT, sock, 0);
350 if (FD_ISSET(i, &read_set)) { /* data on socket */
351 /* can't peek; it's not a socket */
352 Debug((DEBUG_ENGINE, "select: non-socket readable"));
353 event_generate(ET_READ, sock, 0);
359 if (FD_ISSET(i, &read_set)) { /* data to be read from socket */
362 switch (recv(i, &c, 1, MSG_PEEK)) { /* check for EOF */
363 case -1: /* error occurred?!? */
364 if (errno == EAGAIN) {
365 Debug((DEBUG_ENGINE, "select: Resource temporarily "
369 Debug((DEBUG_ENGINE, "select: Uncaught error!"));
370 event_generate(ET_ERROR, sock, errno);
373 case 0: /* EOF from client */
374 Debug((DEBUG_ENGINE, "select: EOF from client"));
375 event_generate(ET_EOF, sock, 0);
378 default: /* some data can be read */
379 Debug((DEBUG_ENGINE, "select: Data to be read"));
380 event_generate(ET_READ, sock, 0);
384 if (FD_ISSET(i, &write_set)) { /* data can be written to socket */
385 Debug((DEBUG_ENGINE, "select: Data can be written"));
386 event_generate(ET_WRITE, sock, 0);
388 if (FD_ISSET(i, &read_set) || FD_ISSET(i, &write_set))
392 case SS_DATAGRAM: case SS_CONNECTDG:
393 if (FD_ISSET(i, &read_set)) { /* data to be read from socket */
394 Debug((DEBUG_ENGINE, "select: Datagram to be read"));
395 event_generate(ET_READ, sock, 0);
397 if (FD_ISSET(i, &write_set)) { /* data can be written to socket */
398 Debug((DEBUG_ENGINE, "select: Datagram can be written"));
399 event_generate(ET_WRITE, sock, 0);
401 if (FD_ISSET(i, &read_set) || FD_ISSET(i, &write_set))
406 assert(s_fd(sock) == i);
408 gen_ref_dec(sock); /* we're done with it */
411 timer_run(); /* execute any pending timers */
415 /** Descriptor for select() event engine. */
416 struct Engine engine_select = {
417 "select()", /* Engine name */
418 engine_init, /* Engine initialization function */
419 0, /* Engine signal registration function (none) */
420 engine_add, /* Engine socket registration function */
421 engine_state, /* Engine socket state change function */
422 engine_events, /* Engine socket events mask function */
423 engine_delete, /* Engine socket deletion function */
424 engine_loop /* Core engine event loop */